Surface condition testing method and apparatus



Jww 1965 .1. c. HINTERMAIER.

SURFACE CONDITION TESTING METHOD AND APPARATUS Filed Jan. 3, 1962 2 Sheets-Sheet l June 29, 1965 J. c. HINTERMAIER SURFACE CONDITION TESTING METHOD AND APPARATUS Filed Jan. 3, 1962 2 Sheets-Sheet 2- sion on a series of drive rolls and support rolls.

United States Patent 3,191,433 SURFACE CONDITION TESTING METHOD AND APPARATUS John C. Hintermaier, Troy, N.Y., assignor to Huyck Corporation, N ew York, N.Y., a corporation of New York Filed Jan. 3, I962, Ser. No. 164,019 8 (Ilairns. (Cl. 73-494) This invention relates to surface testing and more particularly to a method and apparatus for testing the surface condition of a fibrous material.

Testing methods and apparatus of the type to which the present invention is directed, while ofgeneral application, are particularly well suited for determining the finish properties of papermakers felts. As is well-known in the art of papermaking, paper is initially formed from water saturated pulp which is deposited on an open, screenlike structure, customarily referred to as the wire. The wet fibrous web is picked up and transported through various dewatering devices by one or more papermakers felts until the moisture content of the web is reduced to a point at which it becomes self-supporting. The paper is then led through a drier to remove the remaining moisture.

In a papermaking machine, the felts are arranged in the form of endless belts which are mounted under ten- The first felt of the machine, that is, the felt which receives the wet fibrous web from the wire, is usually of a coarser finish than the later, smoother felts. The felts customarily are woven from woolen or synthetic yarns and are then fulled to form a stable and durable structure. Particularly in cases in which critical grades of paper or other products are to be made, one or both surfaces of the felts may he. treated, by brushing, teaseling, and the like, to form a nap and thus present a relatively smooth surface to help reduce surface markings on the paper products corresponding with the woven pattern.

Papermakers felts are expensive items of equipment,

and it is important that they be carefully and scientifically designed and constructed and that their surfaces be maintained in proper condition to insure the desired quality of the paper products. In use, the felt surfaces are subjected to considerable wear, and eventually even the napped surfaces reach a point where they severely mark the paper web, rendering the paper useless for its intended purpose. This is of particular moment in the case of the later, smoother felts, where any substantial irregularities in the felt surfaces produce corresponding markings on the finished product. In addition, the first, or coarse, felt in time marks the web to such an extent that the later felts may not be effective to reduce the markings to an acceptable level.

Heretofore, methods and apparatus for evaluating the surface condition of papermakers felts in most cases involved an examination of the finished paper product. When excessive marking was observed, the papermaking operation was shut down and the felts replaced. Not only were such prior methods and apparatus time consuming and inefficient, but, particularly in the case of relatively high speed papermaking machines, they also frequently necessitated the discarding of considerable quantities of paper which passed through the machine prior to the time the defective felt was discovered.

One general object of this invention, therefore, is to provide a new and improved method and apparatus for 3,191,433 Patented June 29, 1965 testing the surface condition of a papermakers felt or other fibrous material.

More specifically, it is an object of this invention to provide a method and apparatus for ascertaining the surface contours of a papermakers felt in an expeditious manner and while the felt is in an operative position on a papermaking machine.

Another object of the invention is to provide a process for determining the approximate point at which a papermakers felt becomes defective without excessive wastage of the paper product.

A further object of the invention is to provide a method and apparatus for forming permanent impressions of the surface contours of papermakers felts or other materials of varying thicknesses.

Still another object of the invention is to provide a novel apparatus for determining the surface condition of a fibrous material, which apparatus is economical to manufacture and thoroughly reliable in operation.

In one illustrative embodiment of the invention, a deformable member of aluminum foil or the like is positioned adjacent a surface of the fibrous material to be tested. The deformable member and the material are then urged together under increasing pressure to form a permanent impression on the deformable member of the condition of the surface. The thus formed impression is examined and is compared with another impression representative of a known surface condition to ascertain the relative condition of the material being tested.

In accordance with one feature of the invention, the application of pressure between the deformable member and the material being tested is carefully controlled and is arrested when thepressure reaches a predetermined maximum value, thus forming a permanent impression which is substantially independent of the thickness of the material. In certain particularly good arrangements, this maximum value falls within a particular range to thereby insure an extremely accurate representation of the surface under test.

In accordance with another feature of the invention, in certain preferred embodiments, the pressure is applied between a pair of adjacent ends of two pivotally connected arm members, and one of these ends is provided with unique mounting means for maintaining the deformable member in resilient relationship therewith. The arrangement is such that, as these arm ends are urged toward one another, the deformable member moves relative to the associated arm end, the resilstance to this relative movement being increased until such time as the predetermined maximum pressure is attained.

In accordance with a further feature of the invention, in some embodiments, there are provided means operatively associated with the deformable member for indicating the value of the predetermined maximum pressure.

The present invention, as well as further objects and features thereof, will be understood more clearly and fully from the following description of certain preferred embodiments, when read with reference to the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a testing apparatus in accordance with one illustrative embodiment of this invention which is useful in practicing the method of the invention, together with a representative portion of a papermakers felt;

FIGURE 2 is a sectional view taken along the line 22 in FIGURE 1;

FIGURE 3 is a representation of a surface impression of a papermakers felt having an unacceptable finish condition;

FIGURE 4 is a sectional view taken along the line 4-4 in FIGURE 3;

FIGURE 5 is a representation in general similar to FIGURE 3 but showing a surface impression of a paperrnakers felt having an acceptable finish condition; I

FIGURE 6 is a sectional view taken along the line 66 in FIGURE 5; and

FIGURE 7 is a fragmentary side elevational view of a testing apparatus in accordance with another illustrative embodiment of the invention, with certain parts shown in section, together with a representative portion of a papermakers felt.

Referring initially to FIGURE 1 of the drawings, there is shown a deep-throated, plier-like device 10 which includes a pair of elongated arms 11 and 12. Each of these arms is provided with a first pair of integrally formed ears 15 which are spaced a short distance from the right-hand end thereof, as viewed in FIGURE 1, and a second pair of integrally formed ears 16 at the extreme right end. The ears 15 on each arm accommodatea pin 17 which serves to pivotally interconnect the arms intermediate their ends.

The cars 16 on the arm 11 are connected by a pivot pin 20 to one end of an elongated stop member 21, while the ears 16 on the arm 12 are connected by a pivot pin '22 to one end of an elongated stop member 23. These ends of the stop members 21 and 23 are maintained in pivotal relationship with each other by a pin 25. The opposite ends of the members 21 and 23 are each provided with a transverse extension 26 and are respectively affixed to two longitudinally extending handles 28 and 29. The handles 28 and 29 are arranged for manual movement toward and away from each other to pivot the stop members about the pin and thereby produce corresponding movements of the left ends of the arms 11 and 12. Upon movement of the handles toward one another, the extension 26 on the stop member 21 engages that on the stop member 23 to limit further movement of the arms.

Supported at the free end of the elongated arm 11 is a presser assembly 30. This assembly includes a transversely extending adjusting screw 31 which is mounted in a threaded aperture 32 in the arm 11 and is maintained in rigid but adjustable relationship therewith by a knurled nut 33. The screw 31 extends downwardly toward the free end of the elongated arm 12 and is provided at its lower end With a ball 34 which is positioned in a mating socket 34a is a presser foot 35. The foot 35 includes a flat surface 36 (FIGURE 2) thereon of substantially circular configuration.

The free end of the elongated arm 12 includes a transverse aperture 37 which, in the closed position of the device 10 (the position shown in FIGURE 1), is in coaxial alignment with the threaded aperture 32 in the adjacent end of the elongated arm 11. A shaft 38 is slidably disposed in the aperture 37, and the upper end of this shaft, as viewed in FIGURES 1 and 2, is welded or other wise rigidly secured to the lower surface of a substantially horizontal, channel-shaped table 39. This table supports a mat 40 of rubber or other resilient material and is suitably closed at one of the open ends thereof, as by a stop 41.

A permanently deformable member indicated generally at 42 is removably mounted no the resilient mat 40 and is prevented from moving relative thereto by the sides of the table 39 and by the stop 41. The member 42 is formed from a flexible sheet 43 (FIGURES 3-6) which is interposed between two backing members 44. In the illustrated embodiment, the sheet 43 advantageously is fabricated from a metal foil such as aluminum and has a thickness of approximately 0.0015 inch. In other good embodiments, however, the sheet may be made from plastic or other suitable material and may have a thickness which varies widely from that specifically referred to above. 'The backing members 44- illustratively are of cardboard and are each provided with circular apertures 44a to expose portions of the opposite faces of the sheet.

Afiixed to the under surface of the table 39 (FIGURE 1) adjacent the shaft 38- is a guide plate 45. This plate is substantially in the shape of an inverted U, the center portion of which is provided with a suitable aperture through which the shaft 38 extends. One leg 46 of the plate 45 extends downwardly from the table 39 into sliding engagement with the flattened outer end of the arm 12. The other leg &7 of plate 45 is somewhat shorter than the leg 46 and similarly extends in a downward direction into sliding engagement with the upstanding portion 48 of a second guide plate 49 afiixed to the arm 12. This latter guide plate likewise includes a suitable aperture to accommodate the shaft.

The table 39 and the arm 12 are maintained in resilient relationship withv each other by a precompressed coil spring 50. This spring is disposed around the shaft 33, and as best shown in FIGURE 2, one end of the spring bears against the guide plate 45 affixed to the table 39 while the other end engages the guide plate 49 on the arm 12. The compression in the spring tends to urge the table 39 away from the arm '12,- but this movement is normally prevented by a lock nut 51 mounted on the threaded lower end 52 of the shaft 38.

The position of the table 39 relative to the arm 12 is indicated by a pointer 55 (FIGURE 1). This pointer extends in a substantially longitudinal direction with respect to the arm '12 and is pivotally supported interme diate its ends by a pin 56 mounted on a plate 57. The plate 57' is fixedly secured to the arm 12 and is provided with an upstanding sleeve 58 located immediately beneath the table 39. A rod 60 is slidably disposed in the sleeve 58 and is of somewhat greater length, so that it protrudes from both ends of the sleeve. One end of this rod is pivotally secured to the adjacent end of the pointer 55, as at 61, while the other end is maintained in engagement with the lower surface of the table by a light coil spring 62. The spring 62 surrounds the upper portion of the rod 60 and engages a pin 63 affixed to the rod to urge the rod in an upward direction relative to the sleeve and thereby bias the pointer 55 in a clockwise direction about the pivot pin 56, for purposes that will become more fully apparent hereaften.

In use, the device 10 is positioned such that a papermakers felt 65 (FIGURE 1) or other material to be tested is interposed between the presser foot 35 and the deformable member 42 on the table 39, with the surface to be examined facing the deformable member. In cases in which the material is in the form of an endless belt mounted on rollers (not shown), as on a papermaking machine, the device 10 is positioned at any convenient point between these rollers. The handles 28 and 29 are then moved toward each other to initiate pivotal movement of the stop members 21 and 23 about the pivot pin 25 toward the positions shown in FIGURE 1, thus pivoting the arms 11 and 12 about the pin .25 and moving the lefthand ends thereof, as viewed in this figure, toward one another with considerable force.

7 During the pivotal movement of the arms 11 and 12, the flat surface 36 (FIGURE 2) on the presser foot 35 engages the felt 65 and urges the felt surface being tested against the deformable member 42 on the table 39. At this point, primarily because of the cooperation of the ball 34 With the socket 34a, the surface 36 of the presser foot is in precise coplanar relationship with the felt and withthe deformable member. As the pivotal motion of the arms 11 and .12 continues, the table 39 and the arm 12 move toward each other against the gradually increasing resistance of the coil spring 50. The arrangement is such that a gradually increasing pressure is applied between the deformable member and the felt surface, which pressure is dependent upon the resistance of the coil spring to the relative movement between the table 39 and the arm 12.

The relative movement between the table 39 and the arm 12, and hence the pressure between the felt surface under test and the deformable member 42, is measured by a scale 68 which cooperateswith the pointer 55. Thus, as the table 39 and the arm 12 move toward one another, the rod 60 slides in its sleeve 58 to pivot the pointer about the pin 56. The resulting movement of the end of the pointer adjacent the scale 68 provides an indication on the scale of the pressure exerted on the deformable member.

At the time the pressure between the felt 65 and the deformable member 42 reaches a predetermined maximum value, as indicated by the scale 68, the pressure is arrested by releasing the handles 28 and 29, thus forming a permanent impression on the deformable member of the surface under test. For certain particularly satisfactory applications, this maximum pressure advantageously is maintained at a substantially uniform value which is within the range of from about 125 pounds per square inch to 1530 pounds per square inch. By maintaining the maxi mum pressure uniform and within this range, extremely accurate, three-dimensional impressions may be formed on successive deformable members, and these impressions may be compared with each other to ascertain the relative surface condition of the papermakers felt or other fibrous material being tested after various periods of use. Although the use of predetermined maximum pressures outside the 125 to 1530 pounds per square inch range will produce satisfactory results in certain situations, for many applications maximum pressures much below 125 pounds per square inch form impressions which are difficult to examine and accurately evaluate, while impressions formed at maximum pressures above 1530 pounds per square inch frequently are blurred and cannot readily be distinguished from one another. The optimum maximum pressure between the material and the deformable member depends for the most part on the particular characteristics of the material being tested. For many situations, however, it has been found that exceptional results are experienced when the maximum pressure is within the range of from about 200 pounds per square inch to 1000 pounds per square inch.

During the relative movement between the deformable member on the table 39 and the arm 12, the leg 46 of the guide plate 45 slides along the flattened outer end of the arm 12, while the leg 47 of plate 45 slides along the up standing portion 43 of the guide plate 4-9. With this arrangement, the deformable member at all times is maintained in a plane which is perpendicular to the direction of the relative motion, and hence perpendicular to the direction of the applied pressure, and the resulting impression is extremely uniform throughout its exposed surface.

Upon the formation of a permanent impression on the deformable member 42, the member 42 is removed from its position on the table 39. The impression is then examined and is compared with another impression repre sentative of a known surface condition. Representative deformable members having impressions of such known conditions are illustrated in FIGURES 3-6. In FIG- URES 3 and 4, there is shown a deformable member 42a having a permanent impression thereon of a papermakers felt with an unacceptable finish condition which would severely mark a web of paper. FIGURES 5 and 6 are illustrative of a deformable member 421) after the formation of an impression of a felt surface with an acceptable finish condition. The impression of the felt surface being tested may be compared with the impressions on either or both of the deformable members 4211 and 42b to quickly and easily ascertain whether the felt should be replaced.

In cases in which it is desired to vary the range of pressure applied by the device 10, the lock nut 51 on the shaft 38 is rotated to thereby vary the amount of precompression of the coil spring 50, The precompression of the coil spring is adjusted to provide the optimum pressure range for the particular grade of felt or other material to be tested.

The initial position of the presser foot 35 relative to the deformable member 42 may be adjusted in a rapid and straightforward manner to accommodate materials of widely varying thicknesses. To accomplish this adjustment, the knurled nut 33 is loosened, and the screw 31 is rotated in the appropriate direction until the foot 35 reaches its new position.

FIGURE 7 is illustrative of a portion of a testing device 70 useful in connection with the invention. The overall construction andmode of operation of the device 70 is substantially the same as that of the device 10 (FIG- URE 1) described heretofore. However, the device 7! is provided with a pair of witness marks 71 and 72, and the scale 68, the indicating pointer 55 and other parts supported on the plate 57 of the device 10 have been removed, The witness mark 71 is located on one side of the leg 47 of the guide plate 45, while the witness mark '72 is located on the adjacent side of the extension 48 of the guide plate 49. In the open position of the device (the position shown in FIGURE 7), the marks 71 and 72 are spaced apart in a direction parallel to the direction of relative movement between the deformable member 42 and the arm 12 by a distance which is determined by the maximum predetermined pressure to be applied between the deformable member and the felt 65. As the device is operated to urge the deformable member and the felt together under gradually increasing pressure, the guide plates 45 and 49 move toward one another to similarly move the marks 71 and 72 The maximum predetermined pressure is attained at the time these marks coincide, and the handles 28 and 29 (FIGURE 1) are thereupon released and the deformable member examined in the manner described heretofore.

Although the invention has particular utility in the evaluation of the surface characteristics. of papermakers felts, to determine at what point the felts should be replaced, it is also useful in testing various other materials and for other purposes as well. Thus, for example, impressions may be taken in accordance with the invention of textiles, cardboard, paper and other fibrous materials, etc., and these impressions may be taken with substantially equal facility either in the laboratory or under actual manufacuring conditions. The impressions may be used to determine the amount of wear of the material,

to provide comparisons of the effects on surface and inter-ior structure of modifications in yarns, fibers, finishing processes, etc., to measure the yarn spacing and elevation and for a variety of other purposes.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, it being recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. A method of testing the surface condition of a fibrous material which comprises positioning a permanently deformable member movably carried by a support adjacent a surface of said fibrous material, urging said permanently deformable member and said material together under pressure, said deformable member moving relative to said support upon the application of said pressure, applying gradually increasing resistance to the movement of said deformable member to gradually increase said pressure, arresting the application of said pressure when it reaches a. predetermined maximum value, to thereby form a permanent impression on said deformable 7 member of the condition of said surface, and examining the impression of said surface condition.

2. A method'of testing the surface condition of a fibrous material which comprises positioning a permanently deformable member movably carried by a support adjacent a surface of said fibrous material, urging said deformable member and said material together under pressure, said deformable member moving relative to said support upon the application of said pressure, applying increasing resistance to the movement of said deformable member to thereby increase said pressure, arresting the application of said pressure when it reaches a predetermined maximum value, to thereby form a permanent impression on said deformable member of the condition of said surface, examining the impression of said surface condition, and comparing said impression with another impression representative of a known surface condition.

3. A method of testing the surface condition of a papermakers felt which comprises positioning a permanently deformable member adjacent a surface of said felt while it is in an operative position on a papermaking machine, said deformable member being movably carried by a support, urging said permanently deformable member and said felt together under pressure, said deformable member moving relative to said support upon the application of said pressure, applying gradually increasing resistance to the movement of said deformable member to gradually increase said pressure, arresting the application of said pressure when it reaches a predetermined maximum value, to thereby form a permanent impression on said deformable member of the condition of said surface, examining the impression of said surface condition, and comparing said impression with another impression representative of a known surface condition.

4. A method of testing the surface condition of a papermakers felt which comprises positioning a permanently deformable member adjacent a surface of said felt while it is in an operative position on a papermaking machine, said deformable member being movably carried by a support, urging said permanently deformable member and said felt together under pressure, said deformable member moving relative to said support upon the application of said pressure, applying gradually increasing resistance to the movement of said deformable member to gradually increase said pressure, arresting the application of said pressure when its value reaches a predetermined maximum within the range of from about 125 pounds per square inch to 1530 pounds per square inch, to thereby form a permanent impression on said deformable member of the condition of said surface, examining the impression of said surface condition, and comparing said impression with another impression representative of a means to permit relative motion therebetween, said mounting means including pliable support means for carrying said deformable member, and means for operating said pressure applying means, to urge said deformable member and said fibrous material together under gradually increasing pressure and thereby form a permanent impression on said member of the condition of said surface, said deformable member moving relative to said pressure applying means during the application of said pressure.

6. Apparatus for testing the surface condition of a fibrous material comprising, in combination, a deformable member adapted to be applied to a surface of said fibrous 'material, means including a first and second elongated arm pivotally connected intermediate their ends and having one pair of adjacent ends thereof arranged for disposition on opposite sides of said material, a presser 8 foot carried by one of the arm ends of said one pair, support means including a resilient mat for carrying said deformable member, mounting means for movably connecting said support means to the other arm end of said one pair to permit relative motion between said deformable member and said other arm end, and manually operable means for moving the other pair of adjacent ends of said arms toward each other to similarly move said presser foot and said mounting means and thereby urge said deformable member and said fibrous material together under pressure, the application of said pressure being arrested when it reaches a predetermined maximum value, to thereby form a permanent impression on said member of the condition of the surface of said material.

7. Apparatus for testing. the surface condition of a fibrous material comprising, in combination, a deformable member adapted to be applied to a surface of said fibrous material, means including first and second pivotally connected arms having one pair of adjacent ends thereof arranged for disposition on opposite sides of said material, a presser foot adjustably supported by one of the arm ends of said one pair and having a fiat surface thereon, pliable support means for carrying said deformablc member, mounting means for resiliently connecting said support means to the other arm end of said one pair to permit relative motion between said deformable member and said other arm end, said mounting means including spring means for providing a gradually increasing resistance to the movement of said deformable member relative to said other arm end, means for moving the other pair of adjacent ends of said arms toward each other to similarly move said presser foot and said support means and thereby urge said deformable member and said fibrous material together under pressure, said deformable member moving relative to the other arm end of said one pair against the resistance of said spring means to gradually increase said pressure during the movement of said arms, the application of said gradually increasing pressure being arrested when it reaches a predetermined maximum value, to thereby form a permanent impression on said member of the condition of the surface of said material, and means operatively associated with said support means for providing an indication of said predetermined maximum value.

8. Apparatus for testing the surface condition of a papermakers felt comprising, in combination, a substantially planar deformable member adapted to be applied to a surface of said felt, pressure applying means including a first and second elongated arm pivotally connected intermediate their ends and having one pair of adjacent ends arranged for disposition on opposite sides of said "\felt, a presser foot adjustably carried by one of the arm e ds of said one pair, support means including a resilient mat for carrying said deformable member, mounting means for movably connecting said support means to the other arm end of said one pair to permit relative motion between said deformable member and said other arm end, said mounting means including a precompressed coil spring for resisting movement of said deformable member relative to said other arm end-and including guide means for maintaining said deformable member in substantially perpendicular relationship to the direction of said relative motion, manually operable means for moving the other pair of adjacent ends of said arms toward each other to similarly move said presser foot and said support means and thereby urge said deformable member and said felt together under pressure, said deformable member moving relative to the other arm end of said one pair against the resistance of said spring to gradually increase said pressure during the movement of said arms, the application of said pressure being arrested when it reaches a predetermined maximum value within the range of from about pounds per square inch to 1530 pounds per square inch, to thereby form a permanent impression on said member of the condition ofthe surface of said felt, and means oper- 9 10 atively associated with said support means for providing FOREIGN PATENTS an indication of said predetermined maximum value. 358,378 '10/31 Great Britain References Cited by the Exat niner 689908 4/53 Great Bntam UNITED STATES PATENTS V 5 RICHARD C, QUEISSER, Primary Examiner.

2,502,804 4/50 Spencer 81367 X DAVID SCHONBERG, Examiner. 2,651,110 9/53 Dike 100234 X 

1. A METHOD OF TESTING THE SURFACE CONDITION OF A FIBROUS MATERIAL WHICH COMPRISES POSITIONING A PERMANENTLY DEFORMABLE MEMBER MOVABLY CARRIED BY A SUPPORT ADJACENT A SURFACE OF SAID FIBROUS MATERIAL, URGING SAID PERMANENTLY DEFORMABLE MEMBER AND SAID MATERIAL TOGETHER UNDER PRESSURE, SAID DEFORMABLE MEMBER MOVING RELATIVE TO SAID SUPPORT UPON THE APPLICATION OF SAID PRESSURE, APPLYING GRADUALLY INCREASING RESISTANCE TO THE MOVEMENT OF SAID DEFORMABLE MEMBER TO GRADUALLY INCREASE SAID PRESSURE, ARRESTING THE APPLICATION OF SAID PRESSURE WHEN IT REACHES A PREDETERMINED MAXIMUM VALUE, TO THEREBY FORM A PERMANENT IMPRESSION ON SAID DEFORMABLE MEMBER OF THE CONDITION OF SAID SURFACE, AND EXAMINING THE IMPRESSION OF SAID SURFACE CONDITION. 